Why McLanahan Pug Mill Mixers
McLanahan has been manufacturing Pug Mill Mixers since the early 1950s and has applied them to a wide range of blending applications. McLanahan units are intended for continuous feed and discharge requirements where materials from low to high tons per hour capacity requirements result in a uniformly blended discharge.
Pug Mill Mixers are double-shafted paddle shaft machines.
How Pug Mill Mixers Work
Feed solids should be uniformly proportioned by a feeder and or conveyor system prior to entering the feed entry point, which is located at one end of the mixer box that houses the paddle shafts. The paddles are positioned on the shafts at an angle so to advance the materials though the length of the machine during the blending action.
If liquids are to be mixed with drier solids, spray bars with nozzles are often used either in the feed chute above the mixer where the feed solids are transitioning the material from a feeder to the Pug Mill, or are positioned above the mixer shafts immediately after feed solids enter the mixer box. The liquids should be metered under pressure and be regulated by valves for fine-tuning the amount of liquid addition.
Typically, all paddles are used to advance the materials being blended through the mixer box. In some instances during commissioning, a few paddles can be positioned to a neutral or retarding position to increase the retention time, providing more thorough mixing.
Other features depending on the application that can be supplied can include:
- an adjustable dam near the discharge end, which is on the bottom of the mixer box at the end opposite the in feed location. This allows the bed depth of the materials to be varied to provide more efficient blending of materials.
- a variable speed drive for increasing or decreasing paddle shaft speeds to vary the retention time of the materials being mixed.
- Varying shapes of paddles than can be rectangular of fanned shaped to optimize mixing.
Popular Applications for Pug Mill Mixers
Pug Mill Mixers can be used for:
- Any dry solids where it is desired to add water or other liquids to reduce fugitive dust during loading and/or transport.
- Many materials where it is desired to uniformly mix multiple solids and or liquids at high capacities.
- Mixing ultra-fine filter cake from belt filter presses or plate and frame presses with other solids for transport or disposal.
- Blending biosolids, such as dewatered municipal sewage sludge, with bulking agents to provide a uniform blend required in composting systems. Bulking agents may include sawdust, wood chips, shredded rubber tires, corn stalks and wheat straw.
- In the construction or road building industries where a continuous, high capacity mixer is required to blend rock, sand, lime or cement with water and other liquid additives so that road base materials can be properly laid and compacted prior to building highways and earthen dams.
Benefits of McLanahan Pug Mill Mixers
- Fabricated steel mixer box for rigid design
- Removable top covers provide easy access to service the mixer shafts
- Paddle shafts fabricated from rigid structural steel pipe, equipped with steel flights and renewable wear shoes at the feed end
- Paddle shafts flanged on both ends and bolted to stub shafts to facilitate normal maintenance
- Anti-friction roller bearings used at both ends to support the paddle shafts and mounted outboard with a lip-type bearing seal or taconite type seals depending on the application
- Simplified drive arrangements to minimize maintenance requirements
- Guarding on V-belt drive to prevent contact with moving parts
Frequently Asked Questions
What different sizes and models of Pug Mill Mixers does McLanahan offer?
The Blendmaster is McLanahan’s medium-duty Pug Mill Mixer. It can be used to uniformly blend water to many dry materials prior to disposal and control of fine dust. The Blendmaster can be used as a road base mixer for providing a suitable blend of rock, sand, cement, kiln dust or fly ash with water or oil to allow uniform compaction of specified road base materials. The most predominate use of this Mixer is for blending biosolids with bulking agents for composting facilities. Bulking agents have been wood chips, sawdust, corn stalks and shredded rubber tires. The Blendmaster is V-belt driven by two motors that are top- or side-mounted on adjustable base plates.
The Super Blendmaster is selected to mix more-difficult-to-blend materials that require intermeshing paddle shafts. They can be used to efficiently blend varying grades of coal with fuel oil to increase bulk density and BTU value. They are also used to mix solids with other liquids, such as a wetting agent, to produce a controlled slurry. Paddles are designed to be intermeshing and facilitate better mixing and blending when required.
The Pugmaster is McLanahan’s heavy-duty Pug Mill Mixer. It effectively blends dust with various liquids to allow for transport without particulate matter escaping into the atmosphere. When materials do not easily mix, the Pugmaster is often offered. Drives on the Pugmaster feature a heavy-duty gear reducer equipped with taconite seals and flexible shaft type couplings to connect the reducer to the timing gears. Intermeshing paddles allow for a vigorous mixing action.
Key options to consider?
Consider supporting structure, lime/cement storage silos, rock/sand storage bins, feed and conveyor systems.
What other technologies should I consider?
Drum-batch type mixers, plow blenders, paddle type and low capacity batch mixers.